The SNP Analysis Of Callipyge, Meg3 And DLK1 Gene And Their Correlation With Production Performance In Sheep

Using the method of"random sampling in typical colonies", 87 Tan Sheep, 73 Texel, 70 Suffolk and 112 Dorset were sampled respectively in Helan and Yanchi ,in Ninxia Province. The method of PCR-SSCP technique was used to detect the polymorphism of Callipyge, Meg3 and DLK1 gene, and the method of PCR-RFLP technique was used to detect the A→G single-base mutations of Callipyge phenotype, and the correlation between different genotypes of the three genes and production performance was analyzed. The results are as follow:1. The typical A→G single-base mutations of Callipyge phenotype was not detected in four sheep breeds , but the C→T mutation at the 35 bp upstream was detected. Three genotypes(AA, AB and BB)were observed, The mutation rate in Tan Sheep, Texel, Suffolk and Dorset were separately 0.121,0.041,0.329 and 0.054.2. Callipyge gene in sheep was compared with the homologous Callipyge genes in other 6 species obtained from the GenBank, they are goats, cattle, pigs, horses, dogs and rabbits,and a phylogenetic tree was constructed.The result showed that The relationship between sheep and goat is the closest,the relationships between sheep and cattle, pigs, horses,dogs and rabbits are gradually further.3. The method of PCR-SSCP technique was used to detect the partial feagment of Meg3 and DLK1 gene, a number of new mutations were observed.Five mutation points were detected in DLK1 gene, They are the G→C mutation at the 54507 locus, the T→C mutation at the 54553 locus, the C→T mutation at the 54592 locus, the C→T mutation at the 54620 locus and the T→G mutation at the 54638 locus. Five haplotypes(D-1,D-2,D-3,D-4,D-5)were observed. Two mutation points were detected in Meg3 gene,They are the A→G mutation at the 139069 locus and the G→A mutation at the 139128 locus,Three haplotypes(M-1,M-2,M-3)were observed.4. The statistical analysis of SNP loci of Meg3 and DLK1 gene showed that M1 and M2 loci,D2, D3, D4, D5 and D1 loci, D3, D4, D5 and D2 loci, D3 and D5 loci are completely disequilibrium(P<0.01). M1 and M2 loci, D1 and D2 loci have the same gene frequency,genotype frequency, expected heterozygosity and polymorphic information content. Hardy-Weinberg test at 7 SNP loci in Meg3 and DLK1 gene of four sheep groups show that D3 and D5 loci in Texel groups, M1 and M2 loci in Suffolk groups are not agreed with Hardy-Weinberg equilibrium (0.010.05).5. The associations between some facts and growth traits were analyzed. The association between breeds and growth traits is significant. There is no association between sex and growth traits( P>0.05). Further analysis of the correlation between different genotypes and haplotypes of four sheep groups and the production performance shows that Callipyge, Meg3 and DLK1 genes have no relationship with the production performance index in Dorset, Suffolk and Texel populations( P>0.05).The differences between the genotypes,haplotypes of Callipyge, Meg3 genes and the body size index(withers height,body length and heart girth) are significant ( 0.01